nat66_in2out.c

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/*
 * Copyright (c) 2018 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/**
 * @file
 * @brief NAT66 inside to outside network translation
 */

#include <nat/nat66.h>
#include <vnet/ip/ip6_to_ip4.h>
#include <vnet/fib/fib_table.h>

typedef struct
{
  u32 sw_if_index;
  u32 next_index;
} nat66_in2out_trace_t;

static u8 *
format_nat66_in2out_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  nat66_in2out_trace_t *t = va_arg (*args, nat66_in2out_trace_t *);

  s =
    format (s, "NAT66-in2out: sw_if_index %d, next index %d", t->sw_if_index,
            t->next_index);

  return s;
}

vlib_node_registration_t nat66_in2out_node;

#define foreach_nat66_in2out_error                       \
_(IN2OUT_PACKETS, "good in2out packets processed")       \
_(NO_TRANSLATION, "no translation")                      \
_(UNKNOWN, "unknown")

typedef enum
{
#define _(sym,str) NAT66_IN2OUT_ERROR_##sym,
  foreach_nat66_in2out_error
#undef _
    NAT66_IN2OUT_N_ERROR,
} nat66_in2out_error_t;

static char *nat66_in2out_error_strings[] = {
#define _(sym,string) string,
  foreach_nat66_in2out_error
#undef _
};

typedef enum
{
  NAT66_IN2OUT_NEXT_IP6_LOOKUP,
  NAT66_IN2OUT_NEXT_DROP,
  NAT66_IN2OUT_N_NEXT,
} nat66_in2out_next_t;

static inline u8
nat66_not_translate (u32 rx_fib_index, ip6_address_t ip6_addr)
{
  nat66_main_t *nm = &nat66_main;
  u32 sw_if_index;
  snat_interface_t *i;
  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
  fib_prefix_t pfx = {
    .fp_proto = FIB_PROTOCOL_IP6,
    .fp_len = 128,
    .fp_addr = {
                .ip6 = ip6_addr,
                },
  };

  fei = fib_table_lookup (rx_fib_index, &pfx);
  if (FIB_NODE_INDEX_INVALID == fei)
    return 1;
  sw_if_index = fib_entry_get_resolving_interface (fei);

  if (sw_if_index == ~0)
    {
      fei = fib_table_lookup (nm->outside_fib_index, &pfx);
      if (FIB_NODE_INDEX_INVALID == fei)
        return 1;
      sw_if_index = fib_entry_get_resolving_interface (fei);
    }

  /* *INDENT-OFF* */
  pool_foreach (i, nm->interfaces,
  ({
    /* NAT packet aimed at outside interface */
    if (nat_interface_is_outside (i) && sw_if_index == i->sw_if_index)
      return 0;
  }));
  /* *INDENT-ON* */

  return 1;
}

static inline uword
nat66_in2out_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
                      vlib_frame_t * frame)
{
  u32 n_left_from, *from, *to_next;
  nat66_in2out_next_t next_index;
  u32 pkts_processed = 0;
  u32 thread_index = vlib_get_thread_index ();
  nat66_main_t *nm = &nat66_main;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t *b0;
          u32 next0 = NAT66_IN2OUT_NEXT_IP6_LOOKUP;
          ip6_header_t *ip60;
          u16 l4_offset0, frag_offset0;
          u8 l4_protocol0;
          nat66_static_mapping_t *sm0;
          u32 sw_if_index0, fib_index0;
          udp_header_t *udp0;
          tcp_header_t *tcp0;
          icmp46_header_t *icmp0;
          u16 *checksum0 = 0;
          ip_csum_t csum0;

          /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);
          ip60 = vlib_buffer_get_current (b0);

          if (PREDICT_FALSE
              (ip6_parse
               (ip60, b0->current_length, &l4_protocol0, &l4_offset0,
                &frag_offset0)))
            {
              next0 = NAT66_IN2OUT_NEXT_DROP;
              b0->error = node->errors[NAT66_IN2OUT_ERROR_UNKNOWN];
              goto trace0;
            }

          sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
          fib_index0 =
            fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6,
                                                 sw_if_index0);

          if (nat66_not_translate (fib_index0, ip60->dst_address))
            goto trace0;

          sm0 = nat66_static_mapping_get (&ip60->src_address, fib_index0, 1);
          if (PREDICT_FALSE (!sm0))
            {
              goto trace0;
            }

          if (l4_protocol0 == IP_PROTOCOL_UDP)
            {
              udp0 = (udp_header_t *) u8_ptr_add (ip60, l4_offset0);
              checksum0 = &udp0->checksum;
            }
          else if (l4_protocol0 == IP_PROTOCOL_TCP)
            {
              tcp0 = (tcp_header_t *) u8_ptr_add (ip60, l4_offset0);
              checksum0 = &tcp0->checksum;
            }
          else if (l4_protocol0 == IP_PROTOCOL_ICMP6)
            {
              icmp0 = (icmp46_header_t *) u8_ptr_add (ip60, l4_offset0);
              checksum0 = &icmp0->checksum;
            }
          else
            goto skip_csum0;

          csum0 = ip_csum_sub_even (*checksum0, ip60->src_address.as_u64[0]);
          csum0 = ip_csum_sub_even (csum0, ip60->src_address.as_u64[1]);
          csum0 = ip_csum_add_even (csum0, sm0->e_addr.as_u64[0]);
          csum0 = ip_csum_add_even (csum0, sm0->e_addr.as_u64[1]);
          *checksum0 = ip_csum_fold (csum0);

        skip_csum0:
          ip60->src_address.as_u64[0] = sm0->e_addr.as_u64[0];
          ip60->src_address.as_u64[1] = sm0->e_addr.as_u64[1];

          vlib_increment_combined_counter (&nm->session_counters,
                                           thread_index, sm0 - nm->sm, 1,
                                           vlib_buffer_length_in_chain (vm,
                                                                        b0));

        trace0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat66_in2out_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
              t->next_index = next0;
            }

          pkts_processed += next0 != NAT66_IN2OUT_NEXT_DROP;

          /* verify speculative enqueue, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
                                           n_left_to_next, bi0, next0);
        }
      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  vlib_node_increment_counter (vm, nat66_in2out_node.index,
                               NAT66_IN2OUT_ERROR_IN2OUT_PACKETS,
                               pkts_processed);
  return frame->n_vectors;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat66_in2out_node) = {
  .function = nat66_in2out_node_fn,
  .name = "nat66-in2out",
  .vector_size = sizeof (u32),
  .format_trace = format_nat66_in2out_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (nat66_in2out_error_strings),
  .error_strings = nat66_in2out_error_strings,
  .n_next_nodes = NAT66_IN2OUT_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
    [NAT66_IN2OUT_NEXT_DROP] = "error-drop",
    [NAT66_IN2OUT_NEXT_IP6_LOOKUP] = "ip6-lookup",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (nat66_in2out_node, nat66_in2out_node_fn);

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */